[sokoloff]

They are effective in complying with the relevant law: http://www.law.cornell.edu/cfr/text/14/91.519 which specifically requires an oral briefing on "when, where, and under what circumstances smoking is prohibited".

Don't fault the airlines for complying with the law.

[MichaelGG]

I'm faulting the actual presentation and behavior, regardless of who is ultimately to blame. If the law requires wasting everyone's time and attention with so much no smoking signs, then it's probable it wastes effort on other things, too.